1. Field of the Invention
The present invention relates to a technology of making a toner cartridge reusable in an image forming apparatus.
2. Description of the Related Art
An image forming apparatus includes a plurality of consumable image forming components such as an image carrying member and a developing unit. The developing unit includes rotatable components such as a developing roller and an agitating screw that undergo wear and tear over time. The image carrying member also undergoes wear and tear by being frequently exposed to light for image formation. Moreover, the amount of a developer (e.g., a one-component developer or a two-component developer) in the developing unit or the toner concentration in the developer decreases over time. Thus, it becomes necessary to frequently refill the developer or the toner. For that, automating the process of toner refilling or the process of toner carrier replacement has been proposed.
In previous times, one had to rely on a technical serviceman to replace an image carrying member or a developing unit, which has undergone wear and tear, from an image forming apparatus. However, in recent times, the image carrying member and the developing unit are integrally arranged to form a process cartridge that can be detachably attached to an image forming apparatus. As a result, even a common user can replace an entire process cartridge when one or more image forming components therein undergo wear and tear. That enhances the work efficiency of the common user while using the image forming apparatus. Usually, such replaced process cartridges are collected and only those image forming components that have undergone wear and tear are replaced with new image forming components. In this way, the replaced process cartridges can be made reusable thereby saving resources.
Moreover, from the resource saving perspective, the residual toner after an image forming process is collected from an image carrying member and re-conveyed to a developing unit for reuse. However, there is a possibility that the residual toner is in a deteriorated state of quality due to agitation, conveyance, or electrical action during the image forming process. Hence, it is also a common practice to scrap the residual toner as waste toner. Generally, a detachable toner cartridge is used to scrap the waste toner. That is because a toner cartridge is configured by integrally arranging a waste toner collection chamber and a fresh toner storing chamber. Thus, by using such a toner cartridge, there is no need to arrange a waste toner collection chamber and a fresh toner storing chamber separately in an image forming apparatus. The toner cartridge can be easily replaced when the waste toner collection chamber is filled to capacity.
Various techniques have been disclosed to refill fresh toner in a toner cartridge. For example, Japanese Patent No. 3320191 discloses a technique for refilling a toner cartridge in which a fresh toner filling opening and a residual toner discharging opening are created. The fresh toner filling opening is closed by a cap and covered by a holding member. In such a toner cartridge, fresh toner can be refilled by dismounting the holding member, removing the cap, sealing the residual toner discharging opening, filling fresh toner through the fresh toner filling opening, fitting the cap to the fresh toner filling opening, and re-fixing the holding member to cover the fresh toner filling opening. Similarly, Japanese Patent Application Laid-open No. 2003-57933 discloses a technique for refilling fresh toner in a process cartridge by creating an opening in the process cartridge housing, fixing a tubular member in the opening, refilling fresh toner through the tubular member, and fitting a cap to the tubular member.
However, with the recent awareness regarding environmental concerns, emphasis is being given on saving resources by reuse. That also helps in cutting down the manufacturing cost. In that light, it is necessary to configure a toner cartridge with respect to which refilling of fresh toner as well as discharging of residual toner can be easily performed.
Meanwhile, from the image quality perspective, it is also necessary to efficiently remove remaining unused toner from a fresh toner storing chamber in a toner cartridge before refilling the fresh toner. That is because the unused toner remaining in the fresh toner storing chamber for a long time can affect the image density or the background density of an image thereby deteriorating the image quality.